In the industrial market, semiconductor chipsets play a huge role in the transformation of mechanical equipment to electromechanical or purely Electronic equipment. Each market segment can be broken down into many applications, and chip manufacturers will design specific products for each application.

In the industrial market, semiconductor chipsets play a huge role in the transformation of mechanical equipment to electromechanical or purely electronic equipment. Each market segment can be broken down into many applications, and chip manufacturers will design specific products for each application.

The technological advancement in any application field usually includes some minor advancements, and these technological advancements are either continuous or simultaneous. For example, the automation of an application usually requires sensing one or more parameters and then processing them, which will eventually lead to control and/or communication. Technically advanced sensors can improve some parameter specifications, such as higher performance, smaller size, lower power consumption and cost, and higher overall operating efficiency. Similar technological improvements in processing, control types, and communication with the outside world will further improve these parameter specifications.

In order to make the power grid more efficient, sturdier and safer, and to adapt to the needs of modernization, this effort will greatly increase the use of electronic equipment, thereby creating opportunities for innovation, increased functionality, and reduced size and cost. The energy-saving movement requires the integration of traditional power grids with distributed power grids to form an interconnected power grid. Smart meters are an indispensable part of the power and energy fields, and the global semiconductor value in this segment is more than 2 billion U.S. dollars per year. Smart meters are further divided into electric meters, water meters, gas meters and heating meters.

Ultrasound or ultrasound technology has been used in some civil, medical and military fields for more than 100 years. Almost everyone will use medical ultrasound technology in their lifetime. However, its most recent application case is the realization of automation in the industrial and automotive fields. We were surprised to see that this technology has taken a place in a series of truly diverse applications. The non-invasive (non-corrosive) and non-contact characteristics of ultrasonic technology make it ideal for medical, pharmaceutical, military and factory applications.

In the industrial and automotive markets, ultrasonic technology can be found for distance measurement, occupancy detection, level detection, component analysis, flow rate measurement, parking assistance, landing assistance, and trunk opening assistance. Ultrasonic sensors, also called ultrasonic transducers, can work beyond frequencies that humans cannot hear, and their operating frequencies are between 20 kilohertz and several megahertz.

Most ultrasonic transducers are made of piezoelectric materials, and when electrical pulses are applied, mechanical vibrations or ultrasonic waves are generated. Some transducers can also convert mechanical vibrations back to electrical energy. Transducers are roughly divided into three types:

• The transmitter converts electrical signals into ultrasonic waves.
• The receiver converts ultrasonic waves into electrical signals.
• The transceiver can send and receive ultrasonic waves.

After processing the received electrical signal, several relevant components suitable for industrial or automotive applications can be obtained. One of the most common and important components is the ultrasonic time-of-flight (TOF), which refers to the estimation of the round-trip time of the ultrasonic wave from the sensor to the target object, and then from the object back to the sensor. This is the basic principle of using ultrasonic technology in smart meters to measure the flow of water, gas or heating (whether intrusive or non-intrusive), and present consumption data to consumers for billing purposes.

Flow measurement is the quantification (volume or velocity) of liquid or gas flow. The unit of measurement is similar to liters per minute (or seconds or hours) or square meters per second. The range of flow meters is relatively wide, from simple household meters (gas/water/heating) to industrial meters or mixers for hazardous liquids or gases (oil, mining, wastewater treatment, paint and chemicals, etc.).

In structure, the flow meter includes a sensor unit, a measurement unit, and a control/communication unit, each of which can be further divided into mechanical or electronic. Figure 1 compares the different types of flowmeter sensing technologies that make up the sensor unit. Ultrasonic type flow meters have several advantages.

Application of Ultrasonic Technology in Intelligent Flow Measurement

Figure 1: Comparison of liquid or gas flow sensing methods

Flowmeters that use TOF or ultrasonic waves measure the flow rate by calculating the time difference (propagation delay) between the transmitted and received ultrasonic signals. To apply it to flow measurement, designers use a pair of identical transceiver-type transducers to excite them in the upstream and downstream directions. When propagating in the same direction as the fluid flow, the ultrasonic wave propagates faster, and in the opposite direction to the fluid flow, the ultrasonic wave propagates slower. Therefore, at least one pair of transducers is required, but some topologies use more transducers.

Figure 2 shows a typical concept of ultrasonic flow detection, and the placement of the transducer in the pipeline can be selected.

The choice of ultrasonic sensor depends on the type of medium requiring flow rate measurement. Generally, liquid sensing uses higher frequency sensors in the spectrum (> 1 MHz), while gaseous media uses the lower end of the spectrum (

Application of Ultrasonic Technology in Intelligent Flow Measurement

Figure 2: Examples of common topologies for ultrasonic sensing of flow meters and installation positions in pipelines

Figure 3 shows a general pipe design, the transducer is placed at the bottom, there is reflective material to ensure that the ultrasonic signal can be transmitted between the transducer (XDCR1 and XDCR2 in the figure).
Application of Ultrasonic Technology in Intelligent Flow Measurement
Figure 3: Universal flow tube with a pair of transducers installed

Application of Ultrasonic Technology in Intelligent Flow Measurement

Where Δt is TOF, c is the speed of the ultrasonic signal propagating in the medium in the pipeline, v is the flow velocity, L is the propagation length of the pipeline, T12 is the upstream propagation time, and T21 is the downstream propagation time.

There are several ways to determine TOF information, but all methods need to be able to process the output of the transducer. Figure 4 shows a typical output.

Application of Ultrasonic Technology in Intelligent Flow Measurement
Figure 4: Typical response of an ultrasonic transducer when it is electrically excited

The processing of this waveform provides the information needed to solve equations 1 and 2. There are several ways to process waveforms, including time-to-digital conversion (TDC), zero-crossing detection, and waveform capture. Each method has its pros and cons.

Chip vendors use various architectures to solve the problem of ultrasonic flow measurement. Some manufacturers use discrete analog components followed by digital processors. Other manufacturers are trying to integrate analog components into digital processors to form a single-chip solution. In the waveform capture method, a fast analog circuit is used to capture the entire ultrasonic signal, and then an analog-to-digital converter is used to convert the analog signal into a digital signal, and then the digital signal processing algorithm can obtain the TOF information.

Chip vendors use various architectures to solve the problem of ultrasonic flow measurement. Some manufacturers use discrete analog components followed by digital processors. Other manufacturers are trying to integrate analog components into digital processors to form a single-chip solution. In the waveform capture method, a fast analog circuit is used to capture the entire ultrasonic signal, and then an analog-to-digital converter is used to convert the analog signal into a digital signal, and then the digital signal processing algorithm can obtain the TOF information.

Due to technological improvements in ultrasonic transducers, making them cheaper, more accurate, smaller in size, and ubiquitous, ultrasonic technology has been widely used in flow measurement. The advanced integrated analog circuit makes it easier to capture and process the waveform of the ultrasonic transducer in real time, so that accurate TOF information can be obtained. In addition, ultrasonic flow meters are more accurate, smaller in size, and do not have any moving parts, making them an excellent choice for manufacturers to replace mechanical flow meters. However, manufacturers still need to carefully understand the pipeline design and transducer installation and positioning to ensure that all the advantages of ultrasonic technology are fully utilized in flow measurement.

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